1. Field of the Invention
The present invention relates to optical components and, in particular, to optical components that direct multiple optical channels or perform optical switching from one channel to another, including add and drop functions for optical wavelength channels and to methods for manufacturing such optical components.
2. Description of the Related Art
Optical networks use a variety of optical components, including wavelength channel add/drop modules, optical wavelength multiplexer/demultiplexers, optical attenuators, optical isolators and optical switches. Such components are fundamental to the next generation WDM network. To make the network practical, the necessary optical devices generally must be in the form of arrays of optical elements that physically include multiple communication channels. Functional examples of such components are provided in our co-pending applications entitled “Reconfigurable Optical Add/Drop Module,” filed on May 18, 2001, having Ser. No. 09/861,117 and “Switch and Variable Optical Attenuator for Single Or Arrayed Optical Channels,” filed on Jul. 16, 2001, and having Ser. No. 09/907,496, both of which are hereby incorporated by reference as though fully set forth herein.
Present implementations of these components remain bulky and expensive and have low levels of integration, despite the continued efforts of optical component designers to improve the quality and cost-effectiveness of these optical components. The unavailability of reliable and cost-effective components has retarded the implementation of optical networks and has limited optical networks to very high traffic systems.
Currently, one area of focus for the development of commercially practical components is optical interconnect technology, and in particular, free-space optical interconnection, where signals travel through space to communicably connect optical elements with each other. Free-space based optical devices advantageously minimize the use of optically undesirable materials, such as epoxy adhesives, which when present in a light path can cause distortions that reduce component reliability and useful life. Free-space based fiber optic collimators, which are fundamental components for free-space optical interconnection, advantageously operate with a large separation distance, in comparison with the optical wavelength, between communicating collimators and with relatively low signal attenuation or loss. Such collimator arrays include an array of optical fibers that communicate through space with an array of light collimating lenses. Because of the inherent low-loss advantages of these collimator arrays, substantial resources are being applied to make them cost effective to mass-produce and package in optical devices.
Nevertheless, cost-effective and reliable free-space based collimator arrays and the optical devices that could employ them remain unavailable. The steps of performing optical alignment and attachment at each stage of device assembly continue to be difficult and labor-intensive. Misalignment loss in the space between the optical fiber array and collimating lens array due to scattering, divergence and other distortions of light continues to be problematic. Shrinkage and expansion of the adhesives that are used to join the fiber array with the lens array due to adhesive curing, temperature, aging, or other effects are also major issues because of their short and long-term effects on optical alignment. A related issue is the effect of uneven distributions of adhesive that can stress optical elements and reduce overall reliability. When balanced against the manufacturing priorities of yield and manufacturing cost per unit, these issues become even more difficult to overcome.
A need exists, therefore, for optical devices, such as collimator arrays and switching arrays, including optical add-drop switch arrays and variable optical attenuator (VOA) arrays, that can be easily and cost-effectively manufactured for optical communication applications.